1. Technical Field
The disclosure is related to robotic placement of a workpiece, such as a semiconductor wafer, onto a workpiece support in a reactor chamber, and improved calibration of the wafer location.
2. Background Discussion
There is a need for a method of calibrating wafer positioning by a robot under the actual process conditions of chamber pressure, temperature, etc. The problem is to resolve calibration challenges due to inaccessibility of the chamber interior while under actual process conditions, where there is no way to perform a mechanical calibration. As an example, there is a need to calibrate some chambers while at high temperature, high vacuum or other constraints. Such constraints prevent performing the calibration by mechanical means, such as pin dropping mechanisms or micro cameras mounted on a wafer. In some cases, higher accuracy than what mechanical calibration can achieve may be required. Misplacement of a wafer in a process chamber may lead to process excursions, out of specification results in some areas, and makes it difficult to optimize the process.